The invention concerns a cutter knife with an attaching flange and a separating or cutting region, that blends into a cutting edge, the cutter knife being mounted to knife retainers attached to the outer contour of a cylindrical cutterhead drum so as to be parallel to the axis of rotation of the drum and to be in several circular rows.
German Pat. No. 2,737,683 granted 23 Mar. 1978 (corresponds to U.S. Pat. No. 4,061,284 granted to Raisbeck et al on 6 Dec. 1977) and U.S. Pat. No. 4,257,566 granted to Lawrence on 24 Mar. 1981 each reveal an ensilage harvester cutterhead arrangement including a cylindrical drum on which is supported a plurality of knives where each of the knives extends only over a portion of the width of the drum. Each knife is retained in a friction lock in an angular knife retainer welded to the outer surface of the drum. Each knife of the German patent extends evenly mn a single plane while each knife of the U.S. '566 patent has a leading end bent slightly towards the drum from its planar mounting portion so as to define an angle in the order of 165.degree. to 178.degree. with the mounting portion.
U.S. Pat. No. 4,011,998 granted to Holdeman et al on 15 Mar. 1977 reveals a further cutterhead arrangement whose flat knives are retained in several circumferential rows on disk-shaped carriers, thus defining an open design. The knives are attached to the carriers in such a way that their cutting edges may optionally be oriented either parallel or inclined to the axis of rotation of the rotor. The orientation of the cutting edges of the knives with respect to the axis of rotation is a result of the shape or the arrangement of the knife retainers on the carriers.
According to German Pat. No. 1,116,464 granted 2 Nov. 1961, several circumferential rows of planar knives extend between and are mounted to axially spaced disk-shaped carriers and to spiders extending radially between the carriers. The cutting edges of the knives are inclined with respect to the axis of rotation of the cutterhead and sweep an imaginary cylinder as the cutterhead rotates.
The Danish company Taarup has marketed a Model 406 forage harvester having a cutterhead including a closed drum on whose outer circumferential surface knife retainers are welded in such a way that the cutting edges of the knives mounted to the carriers are inclined to the axis of rotation of the cutterhead so as to sweep an imaginary cylinder as the cutterhead rotates.
A somewhat typical representation of a cutterhead design having helically twisted blades that extend over the full width of the cutterhead is disclosed in U.S. Pat. No. 3,805,660 granted on 23 Apr. 1974.
The aforementioned prior art cutterheads suffer from one or more of the disadvantages of having (a) knives arranged with their cutting edges parallel to the axis of rotation of the cutterhead resulting in high power consumption, (b) knives which are helically twisted and thus difficult to manufacture, (c) knives which extend over the entire width of the cutterhead and hence are expensive to replace and/or (d) knives which are difficult to mount.